Hertha Sponer


Duke Faculty | 1936-1965
Department of Physics

At the peak of the Cold War, when the United States Navy wanted to be able to detect the chemical weapons they feared the most, they turned to Duke’s physics maven Hertha Sponer. A pioneer of using molecular spectroscopy and chemical physics to detect unknown substances, Sponer was no stranger to fears from looming wars.

A black and white photo of Hertha Sponer with a group of physicists, including Albert Einstein, sitting on and behind a couch posing for a photo.
Hertha Sponer (left) sits with Albert Einstein and other physicists at a farewell party for her future husband, James Franck, seated in the center of the couch, before he leaves the Kaiser Wilhelm Institute in Germany

Earlier in life, she had to flee oppression and sexism in her native Germany empowered by the election of Adolph Hitler to preserve her scientific career. Sponer found a new home in America, where she became the first woman to hold a faculty post in Duke’s Department of Physics. The chemical detection methods she pioneered at Duke have since been applied to many uses, ranging from weapons detection to medical radiology.

Hertha Sponer was born Sept. 1, 1895, in Neisse Schlesien, a small town that was then part of Prussia, but which got passed about during WWI to land in the hands of Germany. One of her later colleagues, Duke physicist Horst Meyer, described Sponer’s early years as “an example of a woman’s struggle to be recognized and accepted as a scientist.”

During WWI, she started working at age 18 as a governess, and then as a substitute teacher at an elementary school, but at age 22 she insisted on taking the infamous German Abitur test for university admissions a year early and against the advice of her teachers. She not only passed, she received the highest written grade on the physics portion of any student who took the test that year.

Hertha Sponer, it seemed, was born to be a physicist. And she was determined to become one even in a world where only 2.6 percent of renowned American physicists were women, and Nobel Prize winners like Max Planck loudly warned of “serious consequences” to “the generations to come” if the women of Hertha’s generation stepped out of their “calling as mother and housewife” to seek education.

When Hitler rose to power in 1933, female scientists across Europe realized their careers were among his targets. Hitler and his National Socialist regime believed that for women to work outside the home at all — much less to work in science — raged against the laws of nature. But Sponer was already a member of the German physics elite, the tightknit Berlin physics community that included the likes of Albert Einstein and Lise Meitner.

Sponer dropped her assistant professorship at the University of Göttingen in Germany for a temporary visiting professorship in Oslo, Norway, in 1934, but even then, she was not safe to pursue her chemistry in peace. One day a Nazi-leaning journalist in Oslo wrote an article about the atrocity that was women in the workplace, and lauded how “(in Hitler’s Germany) women cannot work anymore.” He used Hertha Sponer as the article’s cautionary centerpiece. Sponer was not only a woman who worked, but a woman who worked in research, and further yet an unmarried woman who worked in a conventionally male field of science. She was therefore the shining emblem of everything wrong.

The next day, “a siege of journalists and their photographers” followed Sponer to work, as she described afterward in a letter to a friend, hounding her for photos and interviews and information about how she could dare to so flagrantly buck nature. Overwhelmed, Sponer refused to reply or apologize to the horde, she said, and so the local German Nazi group, “seized upon (her) case.” Any response from her defending her love of science could jeopardize her passport and get her shipped back to Germany branded as an enemy of Hitler’s vision. She was fighting constant, mounting loneliness and a desire to see her friends back home, but in order to stay in science, she would have to run once again.

Duke University President William Few began to lobby for her to come to North Carolina.

New York University’s Walter W.S. Cook spoke about recruiting faculty for his own university because of the exodus of brilliant German minds who did not fit the Third Reich’s image of genius. “Hitler is my best friend,” Cook said. “He shakes the trees and I collect the apples.”

Of the three women who had worked as physics professors in Germany prior to 1933, two of those three ingenious apples came to Duke. Sponer was one, and Hedwig Kohn was the other. Sponer’s sister Margot, a professor of Romanistic studies, stayed behind, joined the resistance effort, and was murdered by the Nazis.

In America, women were expected to have higher qualifications than men to reach the same levels in academia. While two-thirds of female physicists in 1920 held Ph.D.s, only 78 percent of them were hired into academia, with almost all of those in faculty posts at women-only colleges. In contrast, only one in three male physicists had a Ph.D. at the time, but 81 percent of them held academic posts. Women also were kept at lower-level and non-faculty positions for far longer than the men, according to a review of the careers of women in science in America prior to 1920.

Before she would agree to a post at Duke, Sponer went to great lengths to ensure that she would not be relegated to a lower-level post because of her gender. She insisted on a full professorship “with the possibility of working together with the men.” Even after receiving that promise, she fretted that once she got to Duke they would use her as “a source of cheap labor” as so many other institutions had tried to do. That “would be just dreadful,” she wrote to a friend. Her concern was well-founded: Nobel Prize-winning physicist Maria Goeppert-Mayer had been relegated to a poorly paid role as a research assistant because of her gender after she fled Germany. Duke was not exempt from the practice, as at least one other female Ph.D. physicist had been assigned a staff role.

Thanks to her self-advocacy and the help of President Few, a full professorship was granted to Sponer even though the president of Caltech had tried to convince Few that if he hired a female professor, no male students of quality would ever come to Duke.

Duke also directed aspiring female physicist Nettie H. Coy to Sponer’s new lab to earn her Ph.D., and in Sponer’s words the Duke support staff got “as busy as pretzel bakers” setting up equipment for her. The hard work paid off and it was not long before the Sponer lab began to produce results.

Two people in lab coats and on in a suit holding wire with equipment lined up on the floor of a lab
Hertha Sponer works alongside Wilhelm Hanle (left) and Gunther Cario (right) in an experimental laboratory

Sponer seemed able to imagine the atomic workings of chemicals in a way that let her understand them better than anyone else. She kept in her lab the flower-covered notebooks from classes she especially enjoyed during her time as a student, and her sharp, tightly angled handwriting crammed as much chemistry as possible between meticulous Greek-riddled equations.

She had a tendency to doodle her science visually, and she would sketch out ideas for new experimental setups in pencil, carefully drawing the proper engineering symbols for voltage sources, light sources and resistors in her electrical diagrams. She once sketched energy levels for electrons on the back of a formal letter of thanks from the National Academy of Sciences.

Sponer’s passion was spectroscopy, a method of using light to identify mystery chemicals or examine their physics. She commonly used fluorescence spectroscopy, bombarding chemicals with fluorescent light and measuring how they responded. Many molecules emit light outward when certain wavelengths of light hit them and even when this “glow” is made of light outside the visible spectrum, it can be measured and used to identify the chemical in question.

In one of the setups Sponer designed, she perched a quartz crystal to act as a window on top of a flask of chilled helium. She passed an arc of light through the window and down into the helium flask, then out the other side through a stainless steel tube plunged deep into frigid liquid helium, kept at about -270 Centigrade. The light was reflected past the chemical being tested then angled and split apart by a quartz prism. From there, the spread light was passed back up another tube, then into a spectrograph, and the spectrograph would record the pattern of the beam.

An archival paper emission spectrum record of Benzezne crystal at 4 degree Kelvin
The “glow” of super-chilled benzene, recorded by Sponer on photo paper during her time at Duke. Sponer and other chemists used these molecular photographs to identify molecules and study their structures

Hertha Sponer and other spectroscopy aficionados measured where the spectrograph’s light-sensitive photo paper showed peaks and valleys of brightness and dark, and they were able to compare the locations of these bright white marks to their theoretical calculations of the atomic physics to figure out the structure of the mystery chemical being tested.

Often, these methods were more sensitive and useful than regular tests of chemical composition, and Sponer was an early pioneer. Her techniques were able to distinguish 1,3,5-trichlorobenzene, an ingredient of explosives, from 1,2,4-trichlorobenzene, a precursor to herbicides and poisons, based solely on the different patterns their two closely related shapes made on the photo paper.

Sponer could tell these two nearly identical chemicals apart with a few quartz lenses, a bit of light, some photo paper from Eastman Kodak, and hyper-chilled liquid helium. She could tell whether trace leftover material meant the Department of Defense should prepare for a chemical threat or a large bomb.

The principles of fluoroscopy she investigated are still used today in occupational safety, medical and military applications, where benign light sources are part of compact, portable devices to stimulate unknown materials with harmless light and examine their output spectra. These devices allow their users to see whether the chemicals examined should be feared or swept into the dustbin.

A grainy black and white photo of Hertha Sponer and James Franch with arms locked on the steps of Duke Chapel in front of the doors
Hertha Sponer and fellow physicist James Franck stand in front of the Duke Chapel after their wedding

During Sponer’s time with Duke’s Department of Physics, she not only constructed new experimental setups that let her unravel the mysteries of the microcosmos, she helped to craft a physics department with a culture of kindness, generosity and support. She accepted students of color in a time when that was discouraged, and she loaned students her own money if they had periods of financial struggle.

Later in life, Sponer married fellow physicist James Franck, her former mentor, and the two exchanged their vows in the Duke Chapel. In an ironic twist, the anti-nepotism rules typically used to relegate women to low- or un-paid staff roles if their husbands were faculty, meant that Nobel Laureate Franck had to stay at the University of Chicago rather than join the faculty at Duke.

By the time she died in 1968, Sponer had left in her powerful wake research insights that spawned countless branches of science and investigation, and a passion for science that helped solidify the excellence of Duke’s Department of Physics.